I am not certain of this because I am level 64 and not yet tried the spell in Gukta, but I thought frogloks were the creatures living in Guk, and guktans were those living in Gukta. Two different factions, not getting along with each other necessarily. I would think that using illusion: froglok would give you a faction bonus in Guk, but not at all in the city of Gukta. On the other hand, the quested spell illusion: guktan (level 52 quest, which is presently broken, I am at the final turn-in and can't get Uklo to hand it to me) would increase faction in the city of Gukta. Two different spells, two different illusions (one would look like the frogloks in Guk, the other like the guktan characters we can now play from Gukta). If the GMs will ever fix the spell quest and give me my spell I quested for, I'll update with a note to let you know if the illusion guktan spell is actually what I am thinking it is. But I have seen others using illusion froglok (the non-quested spell from lvl 65) and it does indeed look like frogloks from Guk, NOT like guktans from Gukta. I have not seen anyone using the 52 spell for guktans.
Tovenaar, 64 enchanter, Kane Bayle server